THE ECONOMIC STATUS OF INSECTS AS A CLASS. 561 



the Royal Society and the British Association for investigating the 

 fauna of the Sandwich Islands, which was published in Nature for 

 March 25, 1897. From this report it appears that the introduction of 

 Coccinella repanda from Ceylon, Australia, and China was so success- 

 ful in the extermination of plant lice upon sugar cane and other crops 

 as to obviate all necessity for spraying. The introduction of Crypto- 

 Icemus montrouzieri from Australia resulted in the entire recovery of 

 the coffee plants and other trees which were on the point of being 

 totally destroyed by the scale insect known as Pulvinaria psidii. Eight 

 other introduced species had at the date of writing (November, 1896) 

 been entirely naturalized and were reported as doing good work against 

 certain scale insects. A Chalcis fly, Chalcis obscurata, introduced from 

 China and Japan, multiplied enormously at the expense of an injurious 

 caterpillar which had severely attacked banana and palm trees. Mr. 

 Koebele, when visiting Washington during November, 1898, mentioned 

 a number of other importations of beneficial insects into Hawaii, about 

 which it is as yet too early to speak. 



A very recent instance of an international importation of striking 

 value is the sending of Novius cardinalis from this country to Portugal, 

 where the white or fluted scale has been checked and in many orchards 

 exterminated in the course of a single year. This importation was 

 made by the writer with the invaluable assistance of the California 

 State Board of Horticulture. 



Other experiments in this line are under way. A parasite of certain 

 wax scales, which are abundant and injurious in the South, has been 

 imported by the writer from Italy, with the cooperation of Prof. 

 Antonio Berlese, of the Boyal Scuola di Agricoltura di Portici; while 

 an effort is being made to bring from Europe insects which will prey 

 upon the gipsy moth which has been so great a plague about Boston ; 

 and other parasites of injurious scale insects in foreign countries are 

 being studied with the purpose of eventually obtaining their introduc- 

 tion into the United States. 



AS DESTROYERS OF NOXIOUS PLANTS. 



Just as we have shown how important is the role played by insects 

 in the destruction of cultivated and useful plants, it will be easy to 

 indicate their importance as destroyers of weeds and other noxious 

 plants. We need only mention the common and cosmopolitan thistle 

 butterfly (Pyrameis car did), the equally common milkweed butterfly 

 (Anosia plexippus), the purslane caterpillar ( Copidryas gloveri), the bur- 

 dock beetle (Gastroidea cyanea), and the purslane sphinx moth (Deile- 

 phila lineata) to recall to the mind of the experienced entomologist 

 many other species which do similar work. They are here, as in the 

 former case, perhaps the principal agents in preventing the undue 

 increase of any one species of plant, but as we find here not an effort 

 of man to combat nature, as it were, by increasing the growth and 

 SM 98— —30 



